This invention relates to support structures for supporting large or small areas of flexible materials used in a manufacturing process, and more particularly to a lightweight, inflatable support structure for use with a reusable compaction bag used in a compaction process for fabricating composite parts.
Since the introduction of reusable vacuum bags on large and small composite structures, there has been a need for a support structure that is able to hold the reusable vacuum bag in a desired orientation during the application and usage of the vacuum bag, and which is able to be stored in a compact configuration, together with its attached reusable vacuum bag, when the support structure and vacuum bag are not in use. If a support structure is not used with the reusable vacuum bag, then the lay-up mechanic must lift the bag and position it on a work piece to perform a compaction operation. This can be a time consuming process, depending on the size of the vacuum bag and the shape of the forming tool on which it is being placed.
Structures which have previously been used to support reusable vacuum bags have traditionally been very rigid and heavy, and typically made from metal or aluminum. After the reusable compaction bag is secured to the rigid support structure, the assembly then requires a large storage space (essentially the size of the reusable vacuum bag when in its operative configuration) when the vacuum bag is not being used. With such a rigid structure secured to the reusable vacuum bag, lifting and removing of the support structure/vacuum bag combination also becomes very cumbersome and can often require additional equipment for moving the assembly. Also, since these support structures have traditionally been constructed of rigid materials (i.e., metal or aluminum tubing), if they are dropped or become bent in transit, they will require straightening back to their original shape.
Since presently used support structures are typically made from dissimilar materials from the vacuum bag, such as aluminum, steel, fiberglass or spring steel, fastening of the vacuum bag to the support structure in a manner such that the vacuum bag is able to make continuous contact with the forming tool can also be difficult. In order to keep the forming tool and the vacuum bag support structure together, they are often attached with a hinge along one side of the support structure and the vacuum bag. This makes one side of the forming tool inaccessible to the lay-up mechanic and, if the tool is very large, also creates an ergonomic concern. More specifically, the lay-up mechanic is then required to lift and lower the hinged support structure onto the forming tool by reaching over the forming tool, which can be physically difficult and strenuous for the operator. Also, in many cases where the support structure and the forming tool are attached with a hinge, this will necessitate a mechanism to assist the lay-up mechanic, such as one or more air cylinders or counter balances, in positions to assist in lifting and lowering the hingedly attached support structure and its attached vacuum bag.
Accordingly, it is a principal object of the present invention to provide a support structure for use with a reusable vacuum bag used in fabricating composite parts, where the support structure forms a lightweight, easy to handle support structure which can be easily collapsed into a compact arrangement for storage when the vacuum bag is not needed.
It is still another object of the present invention to provide a support structure to which a reusable vacuum bag can be readily attached, and where the support structure forms a tubular support structure which can be inflated with a pressurized gas or fluid to expand and/or stretch the vacuum bag out into the orientation required for the bag to be placed over a forming tool, and which can be de-inflated to collapse the support frame structure when the vacuum bag is not needed. Such a support structure would allow the vacuum bag to be stored in a compact configuration when not needed and quickly opened into its operative orientation simply by inflating the support structure.
It is another object of the present invention to provide a support structure to which a reusable vacuum bag can be attached, where the support structure forms a lightweight, inflatable and de-inflatable structure comprised of a plurality of tubing segments intercoupled together to form a single support framework which is easily handled and manipulated by a lay-up mechanic.
The above and other objects are provided by a vacuum bag apparatus in accordance with preferred embodiments of the present invention. In one preferred embodiment, the apparatus comprises an inflatable support structure having a flexible mat, reusable vacuum bag secured thereto at various points about the support structure. The support structure is formed from one or more tube-like elements which are secured together to form a single support framework for supporting the vacuum bag.
The tubing from which the support structure is formed may vary in construction, but in one preferred form is comprised of a multi-layer construction consisting of a reinforcement layer, and inner and outer layers sandwiching the reinforcement layer therebetween. The reusable vacuum bag is permanently secured to the support frame.
When a pressurized gas, such as pressurized air, is injected into the support structure through a suitable valve secured thereto, the support structure is inflated and stretches the vacuum bag into the orientation required for the bag to be placed on a forming tool used in a compaction process. When the apparatus is not needed it may be easily de-inflated and folded into a relatively compact form for storage.
A principal advantage of the apparatus is its light weight construction. This makes the apparatus especially easy for a lay-up mechanic to manipulate when lifting and/or positioning the apparatus on a forming tool. An additional advantage is that since the support structure is still somewhat flexible, even when inflated, damage caused by accidental dropping or bumping of the apparatus against other structures, which would ordinarily require straightening of a metal or aluminum support structure, will in most cases cause no damage to the apparatus.